Continuous process for cracking and polymerizing petroleum oils



April 20,1943.

D. G. BRANDT CONTINUOUS PROCESS FOR CRACKING AD POLYMERIZING PETROLUMOILS Filed May 14, 1940 a ina madam.

Patented Apr. 20, 1943 CONTINUOUS PROCESS FOR CRACKING AND POLYMERIZIN GPETROLEUM OILS David G. Brandt, Westfield, N. J., assignor to CitiesService Oil Company, New York, N. Y., a corporation of PennsylvaniaApplication May 14, 1940, lSerial No. 335,059

(Cl. 19d-58) 12 Claims.

This invention relates to a continuous process for cracking andpolymerizing petroleum oils by subjecting heavy residual types oils tohigh temperature and pressure conditions adapted to crack portions ofthe oil to produce gasoline, and polymerize other portions to produce astock of high specic gravity suitable for the production of petroleumcoke.

Many cracking processes produce both high and lower molecular weighthydrocarbons from the charging stock, and many coking processes havebeen developed for coking cracking still resduums. Some combinedcracking and coking processes have been developed in which the chargingstock heated in a pipe still furnace is alleged to be converted intovapors and a nonlowing carbon residue, the latter of which is collectedin an enlarged coke chamber. In many of the cracking operations in whichcoke is produced from petroleum oil, the coke is mostly of lowmarketable quality, and in such processes there seems to be noconsistent elort to control the quality of the coke either from thestandpoint of its marketability or from the standpoint of producing acoke which can be removed from the coking chamber in a satisfactorymannez. Efforts directed to the control of the cracking operation havebeen largely toward increasing the quality or quantity of the gasolineproduced.

The primary object therefore of the present iivention is to provide an-improvednprocess for cracking and polymerizing residual petroleum oilstocks `to produce a hydrocarbon stock of high specific gravity whichcan be converted into a marketable coke.

A further object of the invention is to provide an improved continuousprocess for simultaneously producing gasoline and a petroleum -tar orpitch of high specic gravity which is converted into marketablepetroleum coke.

A still further object of the present invention is to provide animproved polymerization and cracking process for converting residual`petroleum stocks into gasoline and a residue of,high specific gravitysuitable for coking, in which the various features of the process arecorrelated to produce ylighter oils and marketable coke from the stock,with of course the incidental production of some'gas. Y

Accordingly, the improved process of the supera-tmospheric rosive, toprevent corrosion in the apparatus), through a heating zone comprising aheat eX- changer coil mounted in a fractionating tower wherein thecharging stock is heated in indirect heat exchange with vapors producedin the conversion operation, preheating the charging stock to atemperature of approximately 650 F., and subjecting it to pressurecracking and polymerization conditions in an enlarged chamber whereinthe stock mixture is lpassed in intimate contact with high temperaturevapors produced in `another part of the operation to heat the stock forasubstantial period of time to a temperature above 800 F., maintaining abody of the stock in the lower portion of the enlarged chamber toincrease the time reaction, cracking and polymerization .of stock toproduce a residuum having an A. P. I. lgravity of from about 2 to 15,conducting the high temperature vapors, after contact with said stock,on through said enlarged `chamber and then into the lower portion ofsaid fractionating tower wherein they Vare subjected to rectification toproduce a .reflux distillate of high `boiling point and the desiredlower boiling products, passing a portion of the lreflux distillate fromsaid Vfractionating tower into the upper part of said enlarged chamberinintimate Contact With the high temperature vapors passing therethrough,conducting `another portion of the reflux distillate from saidfractionating tower through a pipe still furnace Vand therein heatingthe `same kto a high conversion temperature at a substantial pressure,.conducting the highly ,heated 4products from said pipe still furnacethrough v.a transfer .line and mixing therewith hot heavy liquid oilresidue from the lower portion of said .enlarged chamber to intimatelycontact said Products, thereafter conducting the resulting mixture intothe upper Aporition of one of a plurality of alternate enlarged cokingchambers, separating vapors from unvaporized oil constituents includingsaid residue .in said coking Chamber and vconducting Vthe vapors at ahigh temperature into the lower portion of said enlarged chamber for`effecting said cracking vand polymerizing operation, retaining theunvaporized liquid oil residue ,in said ycoking chamberto be .convertedinto coke, land removing .the vapors from the upper portion 0f Saidfractionating tower and recovering the gasoline constituents ,therefrom-`,Other :featuresand objects of the present 1n- .vention :will he:apparent t0 those .Skilled in the art. imm the iollowixiemcre detaileddescrip-A ducted from a charge supply tank 2 through a line 4, andforced by means of a pump therein,

through a heat exchange coil S-mountedinandextending through afractionating tower 8. If

the charging stock contains suicient sulfur or other corrosive materialsto cause' excessive cor-Y rosion of the apparatus, a small portion oflime may be conveniently introduced into the line 4 l by a line I as aslurry in some of the charging stock. This lime slurry is preferablymade up, in

suitable apparatus, not shown, by mixing a predetermined proportion ofVhydrated lime with a definite proportion of the charging stock. v,

The fractionating tower 8 is preferably of the usual bubbler typeconstruction with the convolutions of the coil 8 mounted in the vaporrspace above the bubbler trays. `The tower is preferably operated at apressure of about 225 lbs. per square inch to condense all of the oilconstituents produced in the cracking operation, of higher boiling pointthan the desired gasoline or pressure distillate product, which isremoved overhead in vapor form, along with the uncondensable gasesthrough a vapor line I2. The gasoline constituents are condensed in acondenser mounted in the line I2, and the resulting Products areconducted into a gas separator I4, from which the fixed or uncondensablegases are discharged through a suitable pressure valve controlled line,While the gasoline or pressure distillate is discharged through a iioatValve controlled line, as shown.

By the time the charging stock has passed through the coil 6, it isheated to a temperature of from about 625 to 660 F., at whichtemperature it is conducted through lines I6 and I8, into themid-portion of an enlarged pressure cracking and polymerizing chamber20, in which the charging stock passes downwardly over a series ofbailie plates in contact with high temperature vapors'` produced inanother part* of the conversion operation.A In the normalA functioningof the apparatus, theoil stock required forthe coil 6 for coolingpurposes, is considerably greater than the requirements for the chamber20, andthe process in general, so that a portion of the preheated stockin the line I6 a valved line 22 and a cooler mounted therein, back tothe charging line 4.V Instead of cycling oil through the line 22, theadditional cooling in the tower 8 may be effected by other means.

The reflux distillate produced in thetower 8,

and which has roughly the boiling range of gas oil, is dischargedthrougha line 24 and-forced into other parts of the apparatus by meanslof a is conducted through pump mounted therein. A portion of thisrefluxV A stock is preferably conducted through a valved 'line 26 and acooler mounted therein and passed into the upper portion of the enlargedpressure chamber 20, where it passes in intimate contact with vapors asit flows downwardly over a. series of baflie plates in the upper part ofchamber 20.

The remainder of the reflux distillate from the tower 8 is conducted onJthrough the line 24 to a pipe still heater-28, where the distillate isconducted at a pressure of approximately 500 lbs. per square inch, rstthrough a convection tube bank 30, and then through a radiant tube bank32. In passing through these tube banks,

the reflux or stock is heated from an inlet tem- Y perature of about'750 F. to a discharge temperature of from about 970 to 10l0 F., atwhich temperature it is conducted through a discharge line 34 into athree-way valve 36, and then through a valved transfer line 38 into theupperportion of an enlarged coking chamber 4t, which is one of aplurality of similar chambers used alternately v to collect liquidresiduum, in accordance with the `process of the present invention.

The charging stock introduced. into the chamber 20 through line I8 issubjected to relatively -high cracking and polymerizing temperatures forva sufficient time to produce a heavy liquid polymer. The resultingmixture of heavy residual stock and lime suspended therein is conductedfrom the bottom of the chamber 20 through a line 42 and forced by meansof a pump mounted therein through a three-way valve 44, and thenthroughy a valved line 46, directly into the trans fer line 38 beyondthe valve therein. 'Ille heavy polymerized stock from the bottom of thechamber 20 has a temperature of from 800 to 865 F. and isyusually equalto from one-fourth to onethird by volume of the stock passing throughthe line 34, so that the temperature of the mixture in line 38 will befrom about 91T-945 F.

The high temperature products conducted from the line 38 into the top ofthe coking chamber 40, 'comprise both liquidand vapor constituents whichare separated in the chamber 40, the liquid constituents and lime beingretained in the chamber to be later converted into coke, While theseparated vapors are conducted through a valved vapor line 48 into athree-way valve 50,fand` then through aconnecting line 52 into thelowerportionv of the pressure cracking and polymeri'zing chamber 20.These vapors will have a temperature of from 885 to 900 F., so that theyare particularly adapted for use in cracking, polymerizing, andotherwise conditioning the heavy charging stock passed into the chamber20 through the line I8. After the high temperature vapors contact thecharging stock in the lower portion of the chamber 20, and theirtemperature has been substantially reduced, they are brought in contactwith reflux distillate introduced through the line 26. This ydistillatewashes the vapors and holds back occluded heavy hydrocarbons for furtherreaction, and is in turn largely revaporized because of the hightemperature maintained in the chamber 20. Y The resulting vapor mixturein the top of the chamber 20 is conducted therefrom at a temperature` offrom 800 to 830 F. through a vapor line 54 and introduced into the lowerpart of the fractionating tower 8.

Theroperations carried out in the chamber 20 may be varied in certaindetails in order to produce a conditioned liquid Vof high specificgravity at the bottom of the' chamber.V For example, Vthe control of thereactions in the chamber. 20 is more readily eiected by passing aportion of lthe heavy charging stock and lime from the line I6 through aconnecting valved line 56 and introducing it directly into the hightemperature vapors in the line 52. This has the effect of cooling thevapors in the line 52, contacting them with lime and of lowering thecontact temperature in the chamber 20. Furthermore, they quality of thebody of high gravity polymerized ma- -terial collected in the bottom'oft the VVchamber -2is'affected' by varying the'p'roportions of 'stockconducted respectively through thev lines: I8 andiSG.

The cracking and:.polymerization: offthe charglng stock4 carriedout. inthe chamber 2'0. is ef'- fect'ed at a pressure of approximatelyA 225lbs. per square-inch, and' at a temperature ofV from 820' to 850 F.,so-that substantialA vaporization isprevented and there is no net lossby vaporization. In atypical operation, topped crudeoil charging stockof about 24 A. P. I. gravity was supplied to-the chamber 2l) intheproportion of about 23 parts through the lineV 56 to about' 57partsthrough the liner I8. While that' portion introducedY into thevaporl line 52 was cracked andpolymerized ataslightly higher temperaturefrom that introduced-into the-chambr 20 through the-line I8, thecombined operations produced a product of optimum quality for conversioninto amarketable coke. In ord-inarypractice, a considerable body ofmaterial is maintained in the lower portion of the chamber4 20' toprovide a.

suitable-soaking timelunder pressure to givea product of from 8 to 11lA; P. I. gravity. This polymerized productl contains no coke and verylittle-free carbon, since the cracking and polymerizing operationcarried out in the chamber 20 iscontrolled to avoid coke-formation. Inconditioning the polymerized material inthe chamber 20, it has beenfoundnecessary to supply a ratherA denite proportion of the preheatedcha-rging stockto thevapor line 52. Attempts to introduce all ofthe-stock'through the line I8 haveresulted inthe production-of a muchpoorer quality of coke from the-polymerized stock.

The transfer line products from' the line 38 are continuously introducedinto the ook-ing chamber 40 until the .chamber has been filled orsubstantially lled with the conditioned polymerized liquid oilvconstituents. Thereafter, the transfer line products are directed by thethreeway valve 36 through an alternate valved transfer line 58 intothe-upper portion of a second coklng chamber 6D which is'of thesame-structure-as the-chamber 48, the'chamb'er 60, ofcourse having beenfreed of coke from' any previous'use in the system. Whenl the-transferline products are directed through the line -58-byjthe valve 38, thevalve-44 will also` be -operatedto conduct the hot heavy polymersv fromthe-line 42 through a connecting line 82 into the line 58, and thethreeway valve 50'will be turned to take' the vaporsfrom the cokingchamber 60 through-a valvedV vaporline 84.

The-accumulation of-lquid in the chambers 4U and Ellis followed by meansof thermocouples- (not shown) installed'in the chambers at variouslevels'tov serve as an indication of the approximate oil' level.'IhermocouplesV locatedv in the vapor space will normally read'veryAclose to the temperature at the upper part of thechamber,

for-example, these couples-may read'from 885 to 895 F. As soon as theliquid level covers one ofthe thermocouples-there-isfa marked drop intemperature from, say, 885 down to-8l0cl F., so that an operator willknow the approximate'oil level and how fast the chamber is lling withthe conditioned oil.

The three-way valves 36, 44 and 50 are-of a Well-known type, each ofwhich may, if desired,

be--setto simultaneously connect into-allthree` oftheir connecting linesat the same time: This may be desirable, asfor example, whenchamber Mliscompletely cut oi from the line 38, thevalve 50 may 'be-used; toreceivevaporsfromf bothchambers 40- and Ill` and-irra-V heating' upperiod: z supply vapors from one;y chamber: totheother..

It will be notedlthat each ofifthe'zlinesag' 58,48; 62, 48 and 845,islprovided'r: with; independentcutoff valves.

berwhich is-cut out' of the systemfor'cleaning..

Thecollecting` chambers'V aref operated under' a. superatmosphericpressurev o'f fromr about, 200'1 tol 275 lbs. per vsquare inch, so`that-immecliatisely after' the chamber 401is'cut out'ot'the--systemandf-the Valves in lines-38, 46.*and248 are-closed,-thepressure on the chamber"is-.reducedaasthe-rstlstep in electingthe'coking-4 of the' hottar'collected in the chamber. by. opening avalve-inl a' run-downlline-Giwhich leadsto a= cooler and sump,I not:sh'oWn'i in thel drawing (the chamber 60v isalsowprovided with a., Sincethe largebody. of liquidi tar in the chamber 40 is ata-.hightem-perature; a.- comprising the*- similar line 66) considerableportion. thereof, lighter constituents, isl vaporized upon. thereduction in pressure, and' such constituents:` are dischargedthrough-the line Il.y The pressure inv chamber 40' is reduced" tosubstantially Vatmospheric, and the-cokng-` of the-body of oilinthechamber is. partially effected, but is completed'- bythe introductionofI steam into the-loWer,por'- tion ofthe chamber, followed-by theintroductionof Water.

When either 'of the chambers-40 or SIl'isgcut-'out of the system forcoking,` and pressure reduced thereon, as foriexample the chamber 40,;steam- (notsuperlfieated)l is' suppliedV from a valved line- 68 andconducted' through one of the lines 10 Which connects-into ashort line-l2on the bottom f water is' admitted from a-valved-supplyfline 14 tovcomplete the-coking operation,` the waterl being admittedlfrom theflineNfthroughlines T0 vand 12, into thelower part-fofthechamberd. The rateof Water supply to-thechamber' is usually controlled by Watching thepressure'developed in the chamber and-preventing the occurrence of apressure-which will in any Way approach that von thewater'line. In thelaterstages of the-coke-production Water is introduced intol the chamberto electits coolingdown-toV a-.point sufficiently. low that it may-beopened'forcoke removal.

Cokeremoval from the chamber 40, and of course, from t'hev chamber lwhenit was cut out of the system, is accomplished'by-any ofthe Well-knownmethodsor means.

After the-chamber'lID-'hasbeen cleaned of coke,-

the manf-heads are replaced, and the chamberis.A

filled with oil from a supply line I64 which fis-con nected into theAlines 10. Thisoil'istheusual charging stock or other oil taken from anysource` and 'supplied-rapidly--to the chamber so-asto ll it quickly,after whichA the chamber is -cold'tested ata highV pressure, f in-orde-r--to insure' safe -operation, when itis subsequently cut backinto theA systemplace of. chamber. 605 After-z the-cham'- ber=6'0`-:hasbeen'llfedewitvh. thef-unvapori?.eei-tarry1 'Ihese valves. v areinstalled?asia'v safety:` feature'to absolutely preventrthe entrance'vof. any' high-temperature-productsA into '.thec'oking cha-m- Thepressure reductionris .effected residue conditioned for ccking, thechamberM) is cut back into the system, While it is still iilled with theoil-introduced from the line 16.

In order to avoid confusion in the supply of steam or waterv and oiltothe-lower portions of the chambers 40 and..6,f.a detachableL-connection v8l) isprovided foreach of, the lines 10. This L-connection80....must. be completely detached from the water line Mor-the steamsupply 68 before oil can be supplied from :the line 15. changing theL-connection 80 in the manner indicated, itv is impossible to supplyboth oil and water or steam at the same time., There is therefore nopossibility ofintroducing water or steam into a chamber after it hasbeen connected into the cracking system.

A few hours before chamber 50 has become lilled with the conditionedtarry residue, and after chamber 40 vhas been cold tested, the switchvalve Ell-is partially turned so that the opening in the 4plugcommunicates with both chambers Hand 60. This places full unit pressureon chamber 40.', which has been'previously filled with cold oil. Oilisthen drawn from chamber d through lines 12, 11a valved line 18 and arelief cooler (not shown) in order to slowly lower the level in thechamber. Hot vapors from. chamber 60 pass through line 64, switchwalve55 and line 43, into the .upper part of the chamber 4D, and serve toforce the oil out of this chamber and also to preheat the chamber. Therate at which oilis withdrawn from the chamber is controlled, so thatthe chamber will be almost empty by the time chamb er `lill haslaccumulated its charge ofhot tarry residue. At thistime thethreeswitchvalves 35, 44 and 50 are turnedv simultaneously to placechamber 40 in the system and cut outchamber 60. The residue in chamber60 is then converted to coke in the manner described above.

When chamber 40 is first cut into the system, it ,will not have had achance to become heated to full operating temperature and consequentlysome of .the vapors from 1ine738 will condense.V The condensatecollected zin chamber 40 is withdrawn when, say V feetofoilhasaccumulated therein.

The chamber may-not beheated sufficiently when thisf vamount ofvcondensate has been formed, so .that a secondbatch of condensate may beallowed to vcollect in the chamber. vWhen the vapor terri--4 perature atthe upper part of the chamber has reached about 890 F., any liquid inthe chamber is quickly withdrawn throughv line 12, and the chamber isfinally shut in by closing the valve in line 12. After nally preparing achamber vin thisv manner, the temperature-of Vthe mixed feed enteringthe chamber is raised about 5 in order to dry out the lower portion ofthe chamber. This latter operation reduces the tarry residue -to theproper consistency so that in the subsequent` coking operationthe bottomof the chamber will contain coke .which can be easily broken, instead ofa `tarry pitch. Although this method for switching chambers has` beenfound very satisfactory and is preferred, other methods may be used. Theempty chamber may be heated with superheated steam or other hot fluidprior to switching it into the system. j

Repeated investigations have shown that the material collected in thecoking chambers from the lines 38 and 53 is iiuid, even 4at the bottomof the chamber. The conditioned and polymerized tarry materialintroduced into the transfer lines frointhe chamber 20 is quickly heatedin the transfer line to a temperature of about l935` F., so that somefurther .polymerization or `condi- ByA SIX

is fluid. Furthermore, an analysis showed that it contained `only about12% of free carbonat the end of the filling. period. The free carbon y.

may run from 9% to about 24%. Y

As an example of a typical operation of the process, a topped crude oil,having a 24 A. P. I. gravity, was introduced through the line` 4,containing ().75 pound of hydrated lime per barrel of oil. This stockwas'introduced at the rate of.

about 160 barrels per hour, heated to a temperature of about 640 F. inthe coil 6, and 80 barrels per hour recycled through the line 22. There-l maining 80..barre1s per hour were conducted through the line, I6,of which about l23 barrels per hour was conducted through the line 56,and

the remainder through ythe `line I8. fr The reflux condensate producedin the tower 8 had an A. P,.I.

gravity of i9 to 21, and approximately 285 barrels ,v hour of this stockat a temperatureof '755 F.;

was conducted to the pipe stillfurnace 28at `a pressure of 490 lbs. persquare inch., VFrom to 2.0 barrels per hour of recycle 'stock was.Aconducted through the'line 26. The hot-tar withdrawn from the chamberwas conducted at a temperature of about 815 F. through the line 42 andsupplied at the rate of about 85 Ybarrels per hour to the transfer line.Al period in excess of 10 hours is required to collect the body of tarin one of the chambers 40.01' 60. l v ,Y

In this instance, the pressure maintained in the Vchambers 40 and. 60was 265vv lbs. per squarev inch, with a pressure of 235 lbs. persquareinch in the pressurercracking chamber 20.Y Gradually lowerpressuresof 225 and 215 lbs. per squareinch were maintained in the tower8 and receiver M,

respectively. The transferV line temperature at the point of dischargeVfrom the pipe still furnace was 985519., and that at the entrance tothe colf:-L

ing chamber 935 F. while the temperature in the upper part of the cokingchamber was 890 l.`

The `vapors conducted from the charnberfzl)` throughthe line 54- rwereatga temperature of 825 F., while those conducted through line `)I2 were420 F. This operation was lcarried outy entirely by the use of the heavytopped crude stock introduced through the line `4, so that theA recyclestock produced in the tower 8 was-obtained fromy theheavier materialY bycracking, did not accumulate in the cracking operation, but wascompletely converted to other products.-

, The pressure distillate recovered amountedto '15% of the topped crudecharge andhad an end;

point ot approximately 7120"V F. The amount of coke produced wasequivalent to ,55- lbs. per bbl. of topped crude `chargedto the unit.This coke was fairly hard, making it. possible `to re.;

cover approximately in the form oflump. The coke vcontained 2-3%ksoluble matter and 8-10% volatile matter. Y y..

Having thus described the invention inY its pretact with petroleum oilvapors having a Sllfcent temperature to crack and polymerize the heavystock, maintaining a pressure of at least about 200 lbs. per square inchin said chamber and preventing substantial vaporization, accumulating asubstantial body of the polymerized stock in the lower portion of thechamber at a temperature in excess of 800 F. to provide a time reaction,continuously withdrawing polymerized stock from said body and quicklyheating it to a temperature of about 935 F., conducting the resultingheated polymerized stock directly into the upper portion of an enlargedcollecting chamber, gradually collecting an enlarged body of liquidpolymerized stock in said chamber for a substantial period of time whileretaining said collected liquid body at an average temperature in excessof 800 F., maintaining a pressure of at least about 200 lbs. per squareinch in said collecting chamber while said polymerized stock iscollected in said body, and thereafter coking the liquid body ofpolymerized stock collected in said collecting chamber by the successivesteps of gradually reducing the pressure thereon over a period of time,passing steam through the collecting chamber from the bottom for asubstantial period of time and thereafter introducing water into thebottom of the chamber for a substantial period of time.

2. The method of converting petroleum oils, which comprises passing 2petroleum distillate stock in a confined stream of restricted crosssection through a pipe still furnace and subjecting it to crackingconditions of temperature and pressure, discharging the resulting highlyheated products from said pipe still furnace at a temperature ofapproximately 1000 F. and mixing therewith a minor proportion of a veryheavy polymerized cil stock having a temperature of at least 800 F., anA. P. I. gravity of from about 8 to 12 and resulting from a crackingoperation in which it has been conditioned under pressure for coking,conducting the resulting mixture into the upper portion of an enlargedchamber in which the vapors and unvaporized liquid oil constituents areseparated at a pressure of at least 200 lbs. per square inch,accumulating the unvaporized liquid oil constituents in said chamberunder conditions adapted to prevent substantial agitation until thechamber is substantially filled with liquid, discharging the separatedvapors from the upper part of said chamber and subjecting them to afractionation operation to separate out the desired gasoline from higherboiling constituents and uncondensable gas, isolating the filled chamberfrom the operation cycle and immediately coking the liquid contents ofthe chamber by the successive steps of gradually reducing the pressurethereon over a period of time, passing steam through the chamber fromthe bottom for a substantial period of time and thereafter introducingWater into the bottom of the chamber for a substantial period of time.

3. The method of converting petroleum oils which comprises passingpetroleum distillate stock in a confined stream of restricted crosssection through a pipe still heater and therein subjecting the stock tocracking conditions of temperature and superatmospheric pressure,discharging the resulting highly heated products of said distillatestock from said pipe still heater through a transfer line and mixingtherewith in said transfer line a substantial but minor proportion of avery heavy polymerized oil stock which has been conditioned for.conversion to coke, conducting the resulting mixture through saidtransfer line at a temperature of about 950 F. into the upper portion ofone of a plurality of enlarged chambers in which a pressure of at least200 lbs. per square inch is maintained and wherein the vapors of themixture are separated from unvaporized tarry oil constituents,continuously supplying said distillate stock to said pipe still heaterand retaining said polymerized tarry oil constituents in said chamberunder quiescent conditions until the chamber becomes substantiallyfilled therewith, thereupon directing the stream of products in saidtransfer line into another of said enlarged chambers and isolating thefilled chamber, continuing the alternate use of said plurality ofchambers as collection chambers to thereby provide a continuous process,immediately upon isolating a chamber filled with liquid residue from theprocess cycle, effecting the coking of its tarry contents by thesuccessive steps of gradually reducing the pressure thereon over asubstantial period of time, then introducing steam into the bottom ofthe chamber for a substantial period, and thereafter introducing waterinto the chamber for a substantial period.

4. In a continuous process for converting petroleum oil, in which areflux distillate produced in the conversion operation is passed in aconfined stream of restrictedcross section through a pipe still furnaceand subjected to a cracking temperature of from 960 to 1010 F. at asubstantial superatmospheric pressure, and in which a topped crude cilstock is subjected to a pclymerizing operation in an enlarged contactchamber by heating it With high temperature gases and vapors produced inthe conversion operation, the improvement which comprises subjectingsaid topped crude oil stock to a polymerizing operation at atemperataure above 800 F. to produce a heavy polymerized tarry residuumWhile preventing substantial vaporization, mingling said heavy tarryresiduum while at a temperature of at least 800 F. with the hightemperature products resulting from the heating of said refluxdistillate and thereby raising the temperature of said `residuum,passing the resulting mixture into the upper portion of an enlargedcollecting chamber in which vapors are separated from unvaporized liquidoil constituents under conditions adapted to prevent substantialagitation of the separated liquid oil, gradually accumulating saidseparated liquid oil constituents in said collecting chamber under highpressure until the chamber is substantially filled with the same,thereupon isolating the said collecting chamber from the conversioncycle by conducting the stream of mixed products into an alternatecollecting chamber, coking the unvaporized liquid o il constituents inthe isolated chamber by gradually reducing the pressure thereon toapproximately atmospheric pressure, thereafter passing steam into thelower portion of the isolated chamber for a substantial period of time,and finally introducing Water into the lower portion of the chamberuntil the contents of the chamber have been coked and the chamber cooledto a point sufficiently low to permit opening of the same and removal ofthe resulting coke therefrom.

5. A continuous process for conditioning heavy petroleum oils to becoked, which comprises introducing fresh topped crude oil into anenlarged pressure cracking and polymerzing chamber and thereinintimately contacting the topped crude oil with high temperature oilvapors Vand effecting the polymerization of said topped crude oil at atemperature between 800 and 900 F., continuously introducingthe toppedcrude oil into said chamber and maintaining it therein under a pressureof approximately 200 lbs. per square inch for a suiiicient period oftime to polymerize the topped crude oil to a heavy tarry liquid producthaving an A. P. I. gravity of from 8 to approximately 11 and having arelatively low free carbon content, conducting hot tarry polymerizedstock from said chamber and heating it quickly to a temperature of fromVabout 915 to 945 F., under a pressure in excess of 200 lbs. per'squareinch then collecting said polymerized stock in a quiescent liquid bodyof the stock over a substantial period of time of at least ten hours,maintaining the collected liquid body of stock at an average temperaturein excess of 800 F. and at a pressure in excess of 200 lbs. per squareinch, and after a sufiicient body of said polymerized stock has beencollected and converted into a` product not containing in excess of fromabout 9% to 24% of free carbon, subjecting the liquid body to cokingconditions to convert the stock into marketable petroleum coke.

6. A continuous process'ior converting corrosive petroleum oils by theVuse of lime wherein the direct heating of the lime with the oil byfiring is avoided, which comprises Vpassing a mixture of hightemperature vapors having a temperature in excess of 800 and produced inthe conversion operation into an enlarged unheated contact chamber inintimate contact with a mixture of a heavy oil and lime to purify saidvapors, maintaining a superatmospheric pressure of at least 200 lbs. persquare inch in said contact chamber to prevent substantial vaporiz'ationof said heavy oil, passing the vaporsV from said contact chamber into afractionating tower and thereinproducing a reflux condensate free oflime, passing said reflux condensate in a confined stream of restrictedcross-section through a pipe still furnace and subjecting it to acracking the resulting highly heated products from substantialsuperatmospheric pressure, conducting the resulting highly heatedproducts from said pipe still furnace into a transfer line andintroducing thereinto and mingling with said products a stream of thehighly heated heavy oil and lime produced in said;contactY chamber,passing the resulting mixture of products and lime in said transferlineinto an unheated separating chamber in which liquid oil constituentsand lime are separated from vapors, and conducting vapors from saidseparating chamber to supply the high temperature vapors introduced intosaid unheated contact chamber.

'7. In a continuous process for converting petroleum oil, in which areflux distillate produced in the conversion operation is passed in aconfined stream of restricted cross section through a pipe stillfurnaceand subjected to a cracking' temperature in the neighborhood of 1000 F.at a substantial superatmospheric pressure, and in which a topped crudeoil stock is subjected to a polymerizing operation in an enlargedchamber by heating it with high temeprature gases and vapors produced inthe conversion operation, the improvement whichV comprises subjecting`said topped crude oil stock to a-polymerizing operation at a temperatureabove 800 F.' to produce a heavy polymerized tarry residuum while preventing substantial vaporization, mingling said heavy tarry residuumWhile at a temperature of at least 800 F. with the high temperatureproducts resulting from Vthe heating of said reflux distillate andthereby raising the temperature of said residuum, passing the resultingmixture into the upper portion of an enlarged chamber in which vaporsare separated from unvaporized liquid oil .constituents underVconditions adapted to prevent substantial agitation of the separatedliquid oil in said chamber, gradually accumulating said separated liquidoil constituents in said chamber'under high pressure until the chamberis substantially filled with the same, thereupon isolating the chamberfrom the conversion' cycle by conducting the stream of mixed productsinto an alternate chamber, and coking the ur'ivapo'r` ized liquid oilconstituents in the isolated chamber by the successiveV steps ofgradually reducing the pressure thereon over a period of time, passingsteam through the isolated chamber fromV the bottom over a substantialperiod of` time, and thereafter introducing vvater into the bottom ofthe isolated chamberfor Va substantial period of time. Y s s Y 8. Acontinuous process as deiinedby claim 'I in which the topped crude oilstock subjected to the polymerizing and coking operations includes Y aminor proportion of lime intimately mingled therein. Y y

` 9. The method of converting petroleum oils as defined by claim 2 inwhich a smallproportion of lime is included in the heavy polymerized oilstock mixed with the highly heated products from the pipe stillYfurnace. V10. The method of converting -petroleum oils as defined byclaim 3 in which a small proportion of' lime is included with'the heavypoly- Y said enlarged chamber and brought in contact 1 with hightemperature oil vapors therein.

DAVID G. BRANDT.

with highY CERTIFICATE CF CORRECTION. Patent No. 2,516,951. v April zo,19M.

DAVID C. BRANDT.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correcti on as follows: Page LA,first column, line 25, for "72, "(7" read 72, 'YO-4; page 6, firstcolumn, line h6,

strike out "ing the resulting highly heated products from" and insertinstead --ng temperature of from 9600 to .LOlOO F. at a; vand that thesaid Letters Patent should be read with this correction therein that thesame may Conform to the record of the case in the Patent Office. I

Signed and sealed this 25th day of May, A. D. 1914.5.

. Henry Van Arsdale v (Seal) Acting,- Commisioner of patents.

